Research published in a leading journal detailed how 14 patients experienced an improvement in their condition following the treatment in Leicester.

When the heart is deprived of oxygen during a heart attack, permanent scar tissue develops.

This can permanently hamper the function of the heart, even if the patient recovers from the attack.

Mr Manuel Galinanes, a heart surgeon at the University of Leicester, is trying a technique which uses bone marrow.

This substance, found inside the large vertebrae, is the source of new immune cells and contains cells which have the ability to grow into many different kinds of cell.

Direct approach

The Leicester team's theory was that injecting the marrow directly into the heart would encourage these cells to turn themselves into smooth muscle cells - and help the weakened muscle.

All the patients they chose had hearts severely damaged by heart attacks.

Their "ejection fractions" - a representation of the heart's ability to pump blood around the body - were all low.

The marrow injections were given directly into heart scar tissue during bypass operations to replace clogged coronary arteries.

Heart function was evaluated before and after.

They found that only six weeks after the treatment, the marrow injection patients were faring better than those patients given only the operation.

Tests carried out 10 months later suggested there remained a benefit.

Thigh source

Mr Galinanes said: "Bone marrow not only can differentiate into heart cells, but also smooth muscle cells, connective tissue cells and other types of cells to reconstitute the entire structure of a tissue."

Another research study transplanted muscle tissue from other parts of the body to help shore up severely-damaged hearts.

The team from the Arizona Heart Institute in Phoenix gave the treatment to 16 patients, all of whom had suffered a heart attack or had heart failure.

The muscle cells were taken from thigh muscle, then encouraged to grow in the laboratory, before being put back.

Ejection fraction scores improved, on average from 22.7% to 35.8% after 12 weeks.

Lead research Dr Nabil Dib said: "We have been able to regenerate dead heart muscle, or scar tissue, in the area heart attack without increasing risk of death."